This data article contains data on the Emiliania huxleyi abundance, phytoplankton composition, in the Barents Sea in summer 2014-2018, and physical and hydrochemical parameters in summer 2017. The data are based on the samples collected on stations, where E. huxleyi blooms were recorded. The physical data included the water temperature, salinity, oxygen concentrations at the surface, and various depths. Data of nutrients concentrations included followed parameters: silicates, phosphates, nitrates, nitrites, ammonium, and dissolved inorganic nitrogen. The nutrients ratios are also given. Data of phytoplankton composition consists of the abundance of diatoms, dinoflagellates, coccolithophores, and small flagellates. The data presented in this article are associated with the research article entitled "Interannual variability of Emiliania huxlei blooms in the Barents Sea: In Situ data 2014-2018" . The related research article examines the influence of abiotic factors such as temperature, salinity, nutrients concentrations, and biotic factors (phytoplankton composition) on E. huxleyi abundance.
Using in situ data of 2014-2018, the summers Emiliania huxleyi blooms in the Barents Sea were studied. The blooms were recorded in the upper mixed layer in July and August every year, during which they spread to cover large areas and were associated with Atlantic waters. The E. huxleyi abundance revealed interannual variability, with the highest values (up to 12 × 106 cells/L) in July 2016. Bloom is characterized by a sharp seasonal thermocline, water surface temperature of about 7.14-11.7 °C, low silicate (0.45 ± 0.08 µM) and nitrogen (0.74 ± 0.16 µM) concentration, high phosphorus concentration (0.09 ± 0.01 µM) and nitrogen to phosphorus ratio significantly below the Redfield ratio. Data confirming the hypothesis of limiting the growth of diatoms by nitrogen concentration are presented. When E. huxleyi bloomed, its biomass exceeded 70% of the total phytoplankton biomass, species diversity was low, and diatoms were practically absent, and dinoflagellates were usually represented by large species.